It does give a breakdown on what the levels of trim are about (in the UK):

"‘Pop Star’ is one of two entry-level models: it’s themed with bright and body colour inserts inside. ‘Easy’ 500Ls start at exactly the same money, but are decked out in more sober hues, and get a couple of extra toys: electric rear windows and parking sensors. Top of the range is the 500L Lounge, starting at £16,395. It’s set apart with a suede dashboard, climate control, automatic lights and rain-sensing wipers."

Also, it mentions the seats:
"Thumbs up to Fiat for finally pulling a decent driving position out of the bag: the 500L’s driver is treated to a far more comfortable pose than the sit-up-and-beg 500 or Panda. The seat is far more comfortable too, if less pretty (though who cares about how a seat looks anyway?)."

I'm already thrilled with the regular 500 Lounge seats. They're perfect for me, not too soft, not too firm, and the heating is so good for my back. I can't imagine the seats being even better!

Laughed at their ending "Verdict" and you can read it yourself at the link. (insert plain winkie face here)